You assigned your own stat points and there were more skill trees, IIRC.
So technically there were more 'builds' available. I liked the Paladin, Barbarian and Assassin classes and played them as fairly vanilla builds myself so I'm not too concerned about the changes but some of the more stat-inclined might be.
Edit: For me Diablo 2 was all about exploring huge dungeons, loot and over-the-top, frenetic fighting. D3 has these things in abundance by the sound of it.